Method for imparting improved adhesion to polyolefin substrates

Abstract

Adhesion to polyolefin substrates of (meth)acrylic films or laminates or of coatings, inks, or paints is improved by forming a first film or sheet of a multi-stage polymer containing a crosslinked rubbery first-stage, applying the first film or sheet under heat and pressure to a polyolefin sheet or film, wherein the polyolefin is not rubber-modified, separating the two films or sheets mechanically to leave a thin tie-layer of the multi-stage polymer at or near the surface of the polyolefin sheet or film, and then laminating to the so-treated polyolefin sheet or film a (meth)acrylic sheet or film or applying a latex, paint, or ink.

I claim: 
     
       1. In the process for adhering polyoIefin substrates to polar polymer films or laminates, the improvement which comprises: a) forming a first film or sheet of a multi-stage polymer containing a crosslinked rubbery first-stage formed predominantly from butyl acrylate, and wherein the second-stage is formed predominantly from methyl methacrylate, and wherein the particle size is from about 2 microns to about 15 microns, and wherein the ratio of first-stage to second-stage polymer is at least 3/2;   b) applying the first film or sheet under heat and pressure to a polyolefin sheet or film, wherein the polyolefin is not rubber-modified;   c) separating the two films or sheets mechanically to leave a thin tie-layer of the multi-stage polymer at or near the surface of the polyolefin sheet or film; and   d) laminating to the tie-layer of the so-treated polyolefin sheet or film a polar polymer sheet or film.   
     
     
       2. The process of claim 1 wherein the polyolefin is polypropylene or a non-rubbery propylene/ethylene copolymer. 
     
     
       3. The process of claim 1 where in the polar polymer is a (meth)acrylic polymer. 
     
     
       4. In the process for adhering coatings, inks, or paints to polyolefin substrates, the improvement which comprises: a) forming a first film or sheet of a multi-stage polymer containing a crosslinked rubbery first-stage formed predominantly from butyl acrylate, and wherein the second-stage is formed predominantly from methyl methacrylate, and wherein the particle size is from about 2 to about 15 microns, and wherein the ratio of first-stage to second-stage polymer is at least 3/2;   b) applying the first film or sheet under heat and pressure to a polyolefin sheet or film, wherein the polyolefin is not rubber-modified;   c) separating the two films or sheets mechanically to leave a thin tie-layer of the multi-stage polymer at or near the surface of the polyolefin sheet or film;   d) applying a latex, solvent-based acrylic paint, urethane-based paint or ink to the tie-layer of the polyolefin sheet or film; and   (e) drying the latex, paint, or ink to an adherent film.   
     
     
       5. The process of claim 4 wherein the polyolefin is polypropylene or a non-rubbery propylene/ethylene copolymer.